unshift(@circular, pop(@circular)); # the last shall be first push(@circular, shift(@circular)); # and vice versa
Circular lists are commonly used to repeatedly process things in order; for example, connections to a server. The code shown above isn’t a true computer science circular list, with pointers and true circularity. Instead, the operations provide for moving the last element to the first position, and vice versa.
sub grab_and_rotate ( \@ ) { my $listref = shift; my $element = $listref->[0]; push(@$listref, shift @$listref); return $element; } @processes = ( 1, 2, 3, 4, 5 ); while (1) { $process = grab_and_rotate(@processes); print "Handling process $process\n"; sleep 1; }
The unshift
and push
functions
in perlfunc(1) and Chapter 3 of
Programming Perl; Section 13.13
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